Membrane Separation And Integration Technology To Treat Metallurgical Enterprise Wastewater And Engineering Demonstration

The wastewater generated from the metallurgical industry contents high concentrations of heavy ions and salts and low pH values,which is harmful to ocean life,live stock,and human beings.The treatment of metallurgical wastewater has received considerable attention as a result of the increasingly stringent environmental legislation.The aim of present study is to develop an integrated process with membrane filtration to treat the wastewater generated from the metallurgical industry so as to realize the water recycle.Several technologies including neutralization,coagulation-flocculation,ultrafiltration(UF),advanced oxidation process(AOP)with sand filtration(SF)and ultrafiltration(UF)were employed to treat the wastewater from one of nonferrous metals companies.It was found that the integrated AOP-SF-UF system was suitable for the acidic wastewater based on the cost and quality analysis of permeate water.For example,the turbidity,chemical oxygen demand(COD)and oil content of the resultant permeation decreased from 4.76NTU,340 mg/L and 1.15 mg/L to 0.04NTU,33.20 mg/L and 0.41 mg/L,respectively.The water quality meets the recycling requirement.UF and desalination technologies such as chemical precipitation,nanofiltration(NF),membrane pervaporation etc.were employed to treat tThe discharge wastewater from the company.Results shew that the desalination rate obtained from the tranditional chemical precipitation methody using sulfurizing reagent was not satisfied.Althoug NF could remove some salts(the conductivity of the feed and permeation 115000 and 83500 S/m,respectively),the permate conductivity was still high.The coagulation-flocculation with membrane pervaperation can realize 70%of water recycling.However,membrane pervaperation technology is still in experimental stageFinally,the integrated AOP-SF-UF system with the capability of 200 m3/d was designed and constructed for the treatment of acidic wastewater from vacuum pump.The permeate obtained was COD<100 mg/L,oil concentration<0.50 mg/L and turbility<0.20 NTU,which met the requirement of water recycling.The rate of water recycling was up to 90%.In addition,the quality of permeate water such as COD had monitored kept stable during the two years of running.Especially,it was found that the operating of PVDF membrane prepared by thermally induced phase separation method(TIPS)for the treatment of acidic wastewater(pH?3)was very stable.Moreover,an economics evaluation shows that it can reduce sewage discharge or save municipal water up to 39000 m3/y.Overall,the full-scale AOPs-SF-UF treatment plant provides a visible and feasible solution to the acidic wastewater.